Rituals of the New Moon- an offhand item crafted by inscriptionists, the click-use is awesome :D I've seen large gray wolves, as well as the "coyote color" sandy wolves. Yes, you can do the ghost-wolf puppy dance while shapeshifted :) The recipe itself drops off of mobs in Silverbrook in Grizzly Hills. It's a permanent item.

Super Simian Sphere- an epic BoP trash drop from raids/heroics in Northrend, and a few mobs around Icecrown/Storm Peaks (such as the Captive Vrykul in the mines). Contrary to what most would assume, this is not a cardgame item (far as I am led to beleive!). It's a permanent item.

Time-Lost Figurine- dropped by Terokk in Terokkar forest. Summoning him requires a time-lost offering, which in itself requires a bunch of scrolls and killing his smaller minions. Farming this trinket will probably require several summons, as well. It's a permanent item.

Magic Eater fish- fishies caught in the Underbelly sewers of Dalaran. They can proc any number of buffs when you spend time eating them, including miscellaneous stat buffs (crit/stam, haste/stam, AP/stam, SP/stam), or turn you into a green whelpling, mini basilisk, or cockroach!

Pygmy Oil- created by alchemists from Pygmy Suckerfish or attainable in the Dalaran fishing daily reward bags, this oil is used to make flasks of pure mojo, guru's elixir, potions of speed and wild magic, and to turn you into a little voodoo gnome when you drink ~4 of them straight!!

Deviate Fish- fished from the Wailing Caverns in the Barrens, eating this fish raw can proc one of several effects: small instant heal or hot, +5 spirit, a short nap, shrink size + stam/str, and "Party Time!" which will cause you to do random emotes for 2 minutes. You can use this fish as a reagent for making Elixir of Giant Growth. You can also cook this fish instead, resulting in the next toy...

Noggenfogger- Purchaseable from a vendor, though you must do a questline to make this available for purchase. Starts and ends at Marin Noggenfogger in Gadgetzan, Tanaris. Drinking this potion can result in a featherfall buff, skeleton shapeshift, or shrink you!

Misc. Items

Don Carlos' Famous Hat- drops off of Don Carlos in heroic Old Hillsbrad. He paths along the road on horseback, his coyote following behind. It's a permanent item.

Unusual Compass- a random drop inside the Dalaran fishing daily bag. All it does is spin you in place: a toy for the really, really easily amused. There is one trick you can perform with this item, however: if you use it while falling, it will momentarily slow you, resetting your fall distance. Used carefully, it can prevent a fall death! It's a permanent item.

Tiny Green Ragdoll- purchased from the toy shoppe in Dalaran. Permanent item, 30-minute cooldown, it's a fun little ragdoll you can place on the ground. It surprised me that this is not a single-use item given its cheap price! I sometimes use it like a smoke flare, to mark a location on the ground (for tanking positions, etc).

Zippy Copper Racer, Trusty, & Heavy-single-use item from the Dalaran Toy Shoppe. Vroom... but short-lived :( Only difference between the 3 is their appearance, to tell them apart when racing with friends.

Paper Flying Machine- simple little fly-around toys that whiz through the air, akin to the balls and the Happy Fun Rock. They are a conjured item, thus will disappear after 30 minutes, so you will have to replenish them. Can be purchased from the Dalaran Toy Shoppe.

Happy Fun Rock- drops out of Dire Maul, works exactly like the leather ball/flying machines. It's a permanent item.

Quest-only ItemsArchmage Vargoth's Staff- click to bring forth your Archmage buddy! It's permanent, as long as you don't turn in the quest. He'll flex and laugh and wave at you, if you emote at him.

Dartol's Rod of Transformation- an alliance-only quest item from Ashenvale, though it is now limited to only being useable within a small area of the zone, unfortunately. You used to be able to use it anywhere, and most alliance players kept the item in their bags permanently to play around with when bored!

Seasonal Items

Romantic Picnic Basket- a drop from the Valentine's hourly gifts, this permanent item has a 3-minute cooldown.

Haunted Memento- a relic from the WotLK release event, it was a random drop from the undead mobs that spawned around Azeroth. If you do not have a pet out, a ghost figure will appear and follow you around! You also get the "haunted" debuff. These are not BoP, and can be tossed around like the leather ball/rock/etc, though they are so rare that few if any people actually play ball with these mementos!

Arcanite Ripper- Hallow's End 2008 BoP item, this dropped off of the special boss in Karazhan in the one week (two instance resets) of the holiday. Few classes can use two-handed axes, but it's definitely good for a giggle to jam out!

Oh my... I've spent so long on horde-side that I'd forgotten about Dartol's. Didn't they make it only work in Ashenvale, though? Like that worg suit you get in Howling Fjord, which my rogue still has because I loved being able to turn into a wolfie so much!

I would add to your list the Arcanite Reaper you could loot on Prince Mirkblood in October. ( http://www.wowhead.com/?item=39769 ) Like the Haunted memento, you cannot loot it anymore and it's BoP but it's a fun item. I always carry it in my bags. :D

Not that its overly important, but the basket has a 3 or 5 min cooldown. I know that the CD is ready the same moment the picnic expires physically which is about 3 mins or so. Just a minor detail. not trying to be obnoxious :]